Chemical reactors can very in design over quite a wide range, depending upon the chemical process in which the reactors are to be used. In certain systems, both reactants and catalyst materials are flowed through the reactor to form the desired chemical products. The products are separated from the catalyst materials, and generally the catalyst materials are regenerated and reused in the reaction process.
U.S. Pat. No. 2,525,925 discloses a fluidized catalytic cracking process in which catalyst particles are flowed with oil feed through a reactor conduit. The resulting products are separated from the catalyst and the catalyst is regenerated through a concentric tube arrangement. Following regeneration, the catalyst is reused to contact additional oil feed.
U.S. Pat. No. 6,200,534 discloses a circulating fluidized bed reactor with a reaction space of an axially annular cross section. The reaction space is surrounded by a second reaction space, which acts as a catalyst regenerator, and which also has an axially annular cross section. The design is considered to make it possible to enable large equipment construction having a small height-to-diameter ratio.
In some cases, conveying particles through tubes such as reaction tubes can cause the particles to become electrically charged. Conveying of charged particles through reactor tubes may be responsible for segregated particle flow, a problem which has been observed in gas-solids or circulating fluidized bed reactors. A problem with segregated flow is that radial distribution of the flowing solid particles can also induce radial non-uniformities in the gas and solid velocity profiles. See, Qi and Farag, “Lateral Motion and Its Effect on Particle Concentration Distribution in the Riser of CFB,” AIChE Symposium Series, No. 29, Vol. 89 (1998), p. 73–80, and Malcus and Pugsley, “A hydrodynamic model for high and low-density CFB riser,” 6th Int. Conf. Circ. Fluid. Beds (1999) Poster Session. These types of non-uniformities can negatively impact a desirable plug flow pattern of solids through a gas solids or circulating fluidized bed reactor. Accordingly, it would be desirable to control solids flow or provide a gas-solids reactor system which more closely operates at plug flow like characteristics.